A file that is not visible by default to normal directory-browsing
tools (on Unix, files named with a leading dot are, by convention, not
normally presented in directory listings). Many programs define one or
more dot files in which startup or configuration information may be
optionally recorded; a user can customize the program's behavior by
creating the appropriate file in the current or home directory.
(Therefore, dot files tend to creep — with
every nontrivial application program defining at least one, a user's home
directory can be filled with scores of dot files, of course without the
user's really being aware of it.) See also profile
(sense 1), rc file.